Conventionally, there have been used many containers of configuration in which, for example, a mouth of a bottle filled with food having fluidity such as mayonnaise, jam and the like is closed with an inner stopper, a seal and the like, and then a cap is put thereon. In a case of such configuration, in order to take a content from a bottle, operations such as removing a cap at first, and after that, opening a pull-tab of an inner stopper, or removing a seal are required, and so, it is pointed out that it may be difficult for an elderly person to remove the pull-tab, or the content of the bottle may stick to a hand or scatter around when removing the seal, and so on, and thus, the usability is poor.
In order to improve this, in recent years, there has been proposed cap assemblies of configuration in which, when removing a cap initially, by rotating temporarily the cap in a direction opposite to a direction of removing to open an inner stopper and then rotating the cap in the direction of removing, it is possible to remove the cap in a state in which the inner stopper is opened (see, Patent Literatures 1, 2 and 3). According to the cap assemblies of the proposals, it is not required to open the inner stopper after removing the cap, and thus, the usability is much improved.